CVE-2026-27456
published 2026-04-03CVE-2026-27456: util-linux is a random collection of Linux utilities. Prior to version 2.41.4, a TOCTOU (Time-of-Check-Time-of-Use) vulnerability has been identified in the…
medium4.7CVSS 3.1
AVLACHPRLUINSUCHINAN
util-linux is a random collection of Linux utilities. Prior to version 2.41.4, a TOCTOU (Time-of-Check-Time-of-Use) vulnerability has been identified in the SUID binary /usr/bin/mount from util-linux. The mount binary, when setting up loop devices, validates the source file path with user privileges via fork() + setuid() + realpath(), but subsequently re-canonicalizes and opens it with root privileges (euid=0) without verifying that the path has not been replaced between both operations. Neither O_NOFOLLOW, nor inode comparison, nor post-open fstat() are employed. This allows a local unprivileged user to replace the source file with a symlink pointing to any root-owned file or device during the race window, causing the SUID binary to open and mount it as root. Exploitation requires an /etc/fstab entry with user,loop options whose path points to a directory where the attacker has write permission, and that /usr/bin/mount has the SUID bit set (the default configuration on virtually all Linux distributions). The impact is unauthorized read access to root-protected files and block devices, including backup images, disk volumes, and any file containing a valid filesystem. This issue has been patched in version 2.41.4.
Affected
5 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | util-linux | < util-linux 2.42-1 (sid) | util-linux 2.42-1 (sid) |
| kernel | util-linux | < 2.41.4 | 2.41.4 |
| msrc | azl3_util-linux_2.40.2-3_on_azure_linux_3.0 | — | — |
| msrc | cbl2_util-linux_2.37.4-10_on_cbl_mariner_2.0 | — | — |
| util-linux | util-linux | < 2.41.4 | 2.41.4 |
CVSS provenance
nvdv3.14.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
osv4.7MEDIUM